As electronic devices become increasingly compact and portable, the need to make precise electrical connections between components on a very small scale increases. Arrays of fine, closely spaced, parallel electrical conductors are often needed to connect arrays of closely spaced, side-by-side pads found on printed circuit boards, liquid crystal displays, display panels, charge-couple devices, or the like.
In electronic devices, electronic components are typically arranged with extreme space restrictions. Therefore, electrical connectors are often required to be flexible and to have closely spaced, parallel conductive stripes provided on a flexible insulating support. See, e.g., U.S. Pat. No. 5,059,262 and U.S. Pat. No. 4,931,598. Other methods of producing parallel conductive stripes include: a) conductive inks, b) thin metal wires, or c) stripes of thin metal films, e.g., deposited through a mask or selectively etched to provide the desired conductor width and spacing.
There are disadvantages inherent in the presently known electrical connector tape constructions. Electrical connector tapes that use conductive inks as the conductive stripes typically have an undesirably high resistance. The manufacture of electrical connector tape using thin metal wires for the conductive stripes requires drawing the metal wires down to size and attaching the wires to a flexible insulating support. Known methods are typically difficult and expensive. Stripes made by means of photolithographic techniques are often complicated and also expensive.
In presently known electrical connector tapes, the tape is often constructed such that the spacing of the individual conductive stripes is the same as that of the terminal pads to which the tape is intended to be bonded. Accordingly, when the bonds are made between the conductive stripes and an array of terminal pads, it is necessary that absolute registration be maintained between the stripes and the pads during bonding. The fine pitch of many arrays of terminal pads makes such registration very difficult. Thus, it is often necessary to use magnifying devices when bonding the electrical connector tape to the terminals. However, if the pitch of the electrical connectors is so fine that one or more conductive stripes will contact a terminal pad during bonding, absolute registration may not be necessary. However, it will still be necessary, in most applications, to maintain a generally parallel alignment to prevent cross-over connections.